Re: coal again!

Bill Payne (
Mon, 12 Apr 1999 22:35:03 -0600

Hi Keith,

Unless I missed it, you have not replied to my response below:

>On Tue, 30 Mar 1999 22:03:57 -0600 (Keith B Miller)
>>I have read his paper. I do not disagree with Gastaldo, of course
>>stigmarian roots and axial systems are locally present.

On Wed, 31 Mar 1999 21:39:23 -0600 Bill Payne <>

>LOCALLY present? I don't remember Gastaldo saying that. Please give
>us the page number and the quote.

This is a critical juncture and one I would like to understand. Please
let me briefly present what I understand Gastaldo to say, and his

On page 102 of his 1984 paper, he presents a diagram of Lepidodendron
Dicentricum Felix (after DiMichele 1981) and Stigmarian Axis system
(after Williamson 1887), and shows "Calculated depth of stigmarian
penetration ... for two commonly encountered angles of divergence
assuming no change in axial direction." The diagram shows nine
stigmarian axial root systems at various angles; the tip of the deepest
stigmarian axial system is five meters below the ground surface.
Significant portions of all but four of the stigmarian axial root systems
are deeper than two meters below the ground surface.

If, as you indicated, you agree with Gastaldo that stigmarian axial root
systems do penetrate the subsurface at varying angles, and coal seams are
formed by in situ trees, then it would follow that coal seams should be
underlain by stigmarian axial root systems. However, you have stated:
"I replied that such would not be expected because rooting is not readily
preserved, and the evidence for paleosols rest with the macro- and
microstructural features. Saturated soils are characteristically not
deeply or intensely rooted soils."

On page 104, Gastaldo writes: "The four main stigmarian axes departing
from the base of the trunk may penetrate the matrix at various angles.
The contention that stigmarian axes always are buried shallowly, that is,
lying parallel or subparallel to bedding, is a generalization. Although
specimens have been documented where the axes are buried shallowly (i.e.
MacGregor and Walton, 1972; and others), numerous specimens have been
excavated which demonstrate that stigmarian axes also grew downwards at
steep angles (i.e. Potonie, 1920; Frankenburg and Eggert, 1969; and
others). Sorby (1875) suggested that the difference in angle of
penetration of stigmarian axes of individual trees might indicate
prevailing wind directions during the Carboniferous. Stigmarian axes
which cross cut bedding at angles up to, and in some cases exceeding, 30
degrees and possess perpendicularly inserted, radiating appendages
('rootlets') have been interpreted to represent preservation in a normal
subterranean attitude (Figure 3).

How do you reconcile your statement that "Saturated soils are
characteristically not
deeply or intensely rooted soils" (your post of Mon, 29 Mar 1999 22:24:48
-0600) with Gastaldo's statements that shallow rooting is a
generalization and rooting cross cutting bedding and even exceeding 30
degrees is not uncommon?

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